Pathways to the Abyss

Working on that graveyard shift

There are no 9 to 5’s on the ship. With several different projects going on, work continues around the clock. Working nights is usually a requirement on research cruises like this. When work time during the day is devoted to ROV diving, which can last up to 60 hours, other analyses must be performed at night. On this leg of the cruise, night shifts have been devoted to trawling and performing CTD transects. After the ROV has been recovered the work begins. This was my experience:

12:30–2:00 AM: The otter trawl was put into the water. It was given time for the wire net to extend and towed for 30 minutes at a depth of about 300 m.

Some of the presorted catch. You can see an amalgamation of anemones and quill worms, as well as a hagfish in the top right. Image courtesy of Walt Gurley, Deepwater Canyons 2013 Expedition, NOAA-OER/BOEM/USGS.

2:00–3:00 AM: The trawling net was hauled up onto the deck and the catch was brought into the science lab for sorting. An otter trawl collects samples from the water column as well as the bottom sediment, so we had quite a collection of vertebrates and invertebrates. There were several types of fish, including flounder, scorpionfish, and tonguefish; crustaceans such as red crab and shrimp; as well as sponges, quill worms, anemones, a squid, an octopus, and a sea star. Sorting is done by (gloved) hand. The research scientists are able to easily identify what is what, and the catch was divided up into about three different containers. Some are only counted while others are collected for preservation and further analysis.

The CTD sensor was placed in the water during this time as well. It is lowered approximately 300 m and slowly brought to the surface again. The CTD takes continuous measurements of various physical parameters of the water, and during its ascent collects water samples from twelve select depth intervals. Upon surfacing, the bottles from the CTD are collected and stored in the cold room for preservation until being processed.

Some examples of our catch: a red crab, the lone sea star, and a flounder (note that these combined pictures are not to scale). Image courtesy of Art Howard, Deepwater Canyons 2013 Expedition, NOAA-OER/BOEM/USGS.

3:00 AM–?: Samples from the catch and CTD bottles were prepared for future analysis back on land. Tissue samples were taken from a red crab, several fish, several anemones, the squid, the octopus, and the sea star for carbon and nitrogen isotopic analysis to aid in our understanding of marine food webs. Other specimens from the catch were preserved in formalin for in-depth identification back in the lab. These samples will serve to help identify spatial patterns in dispersal studies.

The bottles from the CTD were filtered through extremely fine mesh filters. Each of the bottles contains 5 liters of seawater, so this process takes a considerable amount of time. The end product is a filter that will be sampled for chlorophyll and particulate organic matter. This information, in conjunction with the CTD measurements, will provide a better understanding of the different water masses around the deepwater canyons.

I helped with a portion of each of these operations. It was exciting, but I was feeling all the hours I had been awake. Thankfully, I was relieved of my duties around 4:30, but the rest of the science group kept working until the wee hours of the morning. In this line of work each person helps out the other, even if the project is not their own, so everyone can be sure to collect the data they need. Their dedication and cooperation, not to mention their ability to work countless hours, is a great example of real science in action.

On this particular night, the work load was actually lightened. Water samples from the CTD are usually also processed for many other parameters for a research group on the ship studying the complex flow of water masses in the Atlantic. These samples were not required on this particular night, but to get an idea of how much later the crew would have had to work, here are the other parameters: trace metals (neodymium), the oxygen isotopic signature of water, the carbon isotopic signature of dissolved inorganic carbon, nutrients, and radiocarbon. Whew!